the documentary airs tonight on pbs and tomorrow night as well. the book is amazing. i know richard had a chance to see the documentary. he's been raving about it for the last several days. >> so exciting to see this finally come to pass after all these years. >> when you're writing the book you talked about individual women's stories. sort of the horrors that they had to overcome. and sort of what input really helped them. "half the sky" we should mention comes from women holding up half the sky. >> a chinese saying. >> exactly. tell me little bit about what you loved about your research in the book that made you think this needs to be a documentary. >> it really started many, many years ago when we were in china. and we had found out that there were some problems in the countryside with women. we had covered tian men square. we started discovering there were 30 million missing female girls, female babies, from the chinese population. which was a stunning number. >> 30 million. >> 30 million. partly through infanticide. partly through a lot of the chinese mothers abo